P.K. Maiti

Bio: P.K. Maiti is an academic researcher from University of Calcutta. The author has contributed to research in topics: Crystallization & Differential thermal analysis. The author has an hindex of 9, co-authored 18 publications receiving 219 citations.

Plant canopies: bio-monitor and trap for re-suspended dust particulates contaminated with heavy metals

Abstract: Urban and peri-urban vegetation is being considered for air pollution abatement. Appropriate plants with efficiency to adsorb and absorb air-pollutants are the prerequisite for green space development. The contributions of surface morphology towards plant’s ability to function as dust particulate adsorber and distribution of trace elements over the leaves are investigated in the present study. Dust interception efficiency was estimated for two roadside plant species named Ficus benghalensis, and Polyalthia longifolia. Leaves of both the plants are capable of capturing dust in the range of 0.12 mg/cm2 to 1.89 mg/cm2 on either of the leaf surfaces. However, variation in dust capturing capacity between the plants was observed. Leaf surface characters such as roughness, length, frequency of trichomes and frequency of stomata played a significant role in capturing re-suspended dust. Frequency (2 to 4 per 0.0004 cm2) and length (152.5 to 92.1 cm) of trichome showed negative co-relation trend, where as frequency and size of stomata showed positive co-relation trend. Elemental analysis by Scanning Electron Microscope attached with Energy Dispersive X-Ray Spectrometer (SEMEDS) indicated the presence of elements such as Sodium (Na), Magnesium (Mg), Aluminium (Al), Silicon (Si), Chlorine (Cl), Pottasium (K), Calcium (Ca), Iron (Fe), Zinc (Zn) and Arsenic (As). The results support the fact that plant canopies can be used for mitigation and bio-monitoring of air pollution as well.

Synthesis of glycal-based chiral benzimidazoles by VO(acac)2-CeCl3 combo catalyst and their self-aggregated nanostructured materials.

Abstract: VO(acac)2−CeCl3 combo catalyst has been developed for chemoselective cyclocondensation cum oxidation under mild reaction conditions toward synthesis of a new class of optically pure compounds, 2-(2′-C-3′,4′,6′-tri-O-benzyl/methyl-glycal)-1H-benzimidazoles It involves an operationally simple synthetic protocol efficient for the syntheses of a wide range of chiral benzimidazoles in high yields without formation of undesired 1,2-disubstituted and pseudoglycal byproducts Vanadium(V) is found as active oxidant for the chemical processes which is investigated by UV absorption spectroscopy Highly ordered one-dimensional low molecular mass organic nanostructured materials are fabricated by nanocrystallization of the chiral nanoscale building blocks Theoretical calculation by the B3LYP/6-31G** level of theory of the glycal-based chiral benzimidazoles shows out of planar geometry of the 1H-anthra[1,2-d]imidazole-6,11-dione moiety, which is responsible for the strong self-aggregation to generate ultralong nanost

Influence of fluorine content on the crystallization and microstructure of barium fluorphlogopite glass-ceramics

Abstract: The effect of varying the fluorine content on the nucleation and crystallization behavior of barium containing glasses based on the system BaO·4MgO·Al2O3·6SiO2·2MgF2 was investigated by differential thermal analysis (DTA), X-ray diffraction (XRD) and scanning electron microscopy (SEM). Both the crystallization peak temperature (Tp) and activation energies (E) decreased, the Avrami exponent (n) and pre-exponential factor (ν) increased. The results suggest that fluorine increases the rate of diffusion in the glass and promotes initial crystallization in barium fluorphlogopite glasses.

Influence of barium oxide on the crystallization, microstructure and mechanical properties of potassium fluorophlogopite glass–ceramics

Abstract: The influence of barium oxide, heat treatment time and temperature on the crystallization, microstructure and mechanical behavior of the system Bax·K1−2x·Mg3·Al·Si3O10·F2 (where x = 00, 03 and 05) was investigated in order to develop novel, high strength and machinable glass–ceramics Three glasses were prepared and characterized by differential thermal analysis (DTA), X-ray diffraction (XRD), scanning electron microscope (SEM) techniques and some mechanical testing methods The crystallization kinetics of glass–ceramics was also studied Activation energy and Avrami exponent calculated for the crystallization peak temperature (Tp) of three different glass batches The Vickers hardness decreased slightly on formation of the potassium fluorophlogopite and barium fluorophlogopite phases, but decreased significantly on formation of an interconnected ‘house of cards’ microstructure

SEMEDS: An important tool for air pollution bio-monitoring

Abstract: Plant canopies act as absorbers of air-borne dust particles. Characterization of the dusts present over the leaf surfaces can indicate the nature of contaminant present in the surrounding area and possible sources as well. Dust particulates get adsorbed on both the surfaces of leaves, however more dust particulates get deposited on the upper surface. These dusts contain many inorganic elements, which were analyzed in the present study. For the present investigation, SEMEDS technique used to characterize the dusts adsorbed over the leaf surfaces. Using SEMEDS the samples were analyzed by two types of methods i.e. point analysis and elemental mapping. Both the methods showed the presence of elements like Si, Al, Fe, Mg, and Ca in the dusts adsorbed over the leaf surfaces. Thus, SEMEDS can be used for in situ air pollution monitoring using tree leaves from the area concerned.

Health risk implications of potentially toxic metals in street dust and surface soil of Tehran, Iran

Abstract: In this study a total of 30 street dusts and 10 surface soils were collected in the central district of Tehran and analyzed for major potentially toxic metals. Street dust was found to be greatly enriched in Sb, Pb, Cu and Zn and moderately enriched in Cr, Mn, Mo and Ni. Contamination of Cu, Sb, Pb and Zn was clearly related to anthropogenic sources such as brake wear, tire dust, road abrasion and fossil fuel combustion. Spatial distribution of pollution load index in street dust suggested that industries located south-west of the city intensify street dust pollution. Microscopic studies revealed six dominant group of morphological structures in calculation of the exposurethe street dusts and surface soils, with respect to different geogenic and anthropogenic sources. The BCR (the European Community Bureau of Reference) sequential extraction results showed that Sb, Ni, Mo, As and Cr bonded to silicates and sulfide minerals were highly resistant to dissolution. In contrast, Zn, Cd, and Mn were mostly associated with the exchangeable phase and thus would be easily mobilized in the environment. Cu was the most abundant metal in the reducible fraction, indicating its adsorption to iron and manganese oxy-hydroxides. Pb was equally extracted from exchangeable and reducible fractions. Anthropogenic sources related to traffic apparently play a small role in Cr, Ni and Mo contamination and dispersed them as bioavailable forms but with reduced mobility and bioavailablity due to high potential of complexation and adsorption to organic matter and iron and manganese oxy-hydroxides. Calculated Hazard Index (HI) suggests ingestion as the most important pathway for the majority of PTMs in children and dermal contact as the main exposure route for Cr, Cd and Sb for adults. The HIs and fractionation pattern of elements revealed Pb as the sole element that bears potential health risk in street dust and surface soil.

A review on phytoremediation of contaminants in air, water and soil.

Abstract: There is a global need to use plants to restore the ecological environment. There is no systematic review of phytoremediation mechanisms and the parameters for environmental pollution. Here, we review this situation and describe the purification rate of different plants for different pollutants, as well as methods to improve the purification rate of plants. This is needed to promote the use of plants to restore the ecosystems and the environment. We found that plants mainly use their own metabolism including the interaction with microorganisms to repair their ecological environment. In the process of remediation, the purification factors of plants are affected by many conditions such as light intensity, stomatal conductance, temperature and microbial species. In addition the efficiency of phytoremediation is depending on the plants species-specific metabolism including air absorption and photosynthesis, diversity of soil microorganisms and heavy metal uptake. Although the use of nanomaterials and compost promote the restoration of plants to the environment, a high dose may have negative impacts on the plants. In order to improve the practicability of the phytoremediation on environmental restoration, further research is needed to study the effects of different kinds of catalysts on the efficiency of phytoremediation. Thus, the present review provides a recent update for development and applications of phytoremediation in different environments including air, water, and soil.

Copper-catalyzed, one-pot, three-component synthesis of benzimidazoles by condensation and C-N bond formation.

Abstract: Benzimidazoles were synthesized by the copper-catalyzed, one-pot, three-component reaction of 2-haloanilines, aldehydes, and NaN3. The reaction was optimized when 2-iodo- or 2-bromoanilines (1.0 equiv), aldehydes (1.2 equiv), NaN3 (2.0 equiv), 5 mol% of CuCl, and 5 mol % of TMEDA were reacted in DMSO at 120 °C for 12 h. Good yields resulted, and the reaction showed tolerance toward functional groups such as ester, nitro, and chloro. Aliphatic and heteroaromatic aldehydes also afforded the desired products in moderate to good yields.

Particulate matter pollution capture by leaves of seventeen living wall species with special reference to rail-traffic at a metropolitan station

Abstract: Atmospheric Particulate Matter (PM) constitutes a considerable fraction of urban air pollution, and urban greening is a potential method of mitigating this pollution. The value of living wall systems has received scant attention in this respect. This study examined the inter-species variation of particulate capture by leaves of seventeen plant species present in a living wall at New Street railway station, Birmingham, UK. The densities of different size fractions of particulate pollutants (PM1, PM2.5 and PM10) on 20 leaves per species were quantified using an Environmental Scanning Electron Microscope (ESEM) and ImageJ image-analysis software. The overall ability of plant leaves to remove PM from air was quantified using PM density and LAI (Leaf Area Index); any inter-species variations were identified using one-way Anova followed by Tukey’s pairwise comparison. This study demonstrates a considerable potential for living wall plants to remove particulate pollutants from the atmosphere. PM capture levels on leaves of different plant species were significantly different for all particle size fractions (P

Glass-Ceramics in Dentistry: A Review.

Abstract: In this review, we first briefly introduce the general knowledge of glass–ceramics, including the discovery and development, the application, the microstructure, and the manufacturing of glass–ceramics. Second, the review presents a detailed description of glass–ceramics in dentistry. In this part, the history, property requirements, and manufacturing techniques of dental glass–ceramics are reviewed. The review provided a brief description of the most prevalent clinically used examples of dental glass–ceramics, namely, mica, leucite, and lithium disilicate glass–ceramics. In addition, we also introduce the newly developed ZrO2–SiO2 nanocrystalline glass–ceramics that show great potential as a new generation of dental glass–ceramics. Traditional strengthening mechanisms of glass–ceramics, including interlocking, ZrO2–reinforced, and thermal residual stress effects, are discussed. Finally, a perspective and outlook for future directions in developing new dental glass–ceramics is provided to offer inspiration to the dental materials community.